Fig. 7.

(A) Concentrations of aqueous, sorbed, and total Si released from unoxidized (combined time-0 and abiotic controls) and microbially oxidized quartz diorite (A, B, and C) after 864 d of incubation. (B) Concentrations of HNO₃-extractable cations released from unoxidized microbially oxidized samples (A, B, and C). For both graphs, n = 6 for microbially oxidized samples (duplicate cultures from 3 inocula after 864 d), and n = 10 for unoxidized (duplicate cultures from time 0 for 3 inocula and abiotic control and the abiotic control after 864-d incubation). Two-tailed P values for unpaired t test between unoxidized and microbially oxidized are indicated. *P < 0.05; **P < 0.01; ***P < 0.001. ns, not significant.